How things measure up is pretty important to us. We don’t just look at objects, we automatically scale them in our minds, guessing about width, height, and how they might fit in our world.

We make these assumptions because few of us carry rulers in our back pockets (where would we put our phones?), and you better be a Property Brother if you’re in the habit of carrying a tape measures on your belt.

If only there was a subtler way to have the power of dimensioning in your pocket.

The $149 version, which I tested, also doubles as a retractable pen (there’s a pen-free $99 version), so there’s even more reason to always have 01 with you.

The key to Instrumment 01’s measuring ease is the rolling ring on the end of the device.

Image: lance ulanoff/mashable

Battery-powered, the mostly aluminum 01 uses a laser, a rolling ring, and a companion app to let you measure on any surface. To use it, you pair it via Bluetooth with your iOS or Android phone, open the app, place your finger on the end for three seconds to activate the pen, and then, holding it in one hand, roll the back end along any surface to measure it. On the app, the numbers go up as the pen edge rolls along the surface. The laser shoots a precise red beam out of the 01’s back end. You use it to align with the start and finish edge of whatever you’re measuring.

If you want to measure the height and width of, say, a painting, you can capture and save both those measurements in one file. For a box, you can add height, as well. You can title these measurements — “This is a box!” — add notes, and store them in the cloud.

Getting started

Let’s begin with a few things I didn’t like about 01. First, the packaging didn’t adequately warn me about the laser, so when I powered up the pen by holding my finger on the back end for a few seconds and then removed my digit, I found myself staring directly into the red beam. I can’t imagine this is beneficial to my corneas.

The measuring stick even hides a pen. The tip can also be swapped out for an iPad stylus tip or lead pencil.

Image: lance ulanoff/mashable

Second, the app wouldn’t let me finish setup without signing up with Instrumments. I get that they have a cloud-based measurement data storage service — but there’s an offline option, so I don’t have to sign up with them.

Measure this

As I mentioned above, measuring something is simply a matter of lining up the red laser line with the starting edge of the measurement subject (making sure that the double “XX” on the pen’s back is facing you), and then slowly dragging the pen to the right as the measure wheel smoothly spins on the back end. (That ring acts like a tiny contractor’s measurement wheel). To add another dimension, I simply tapped on the top of the pen and the app would switch to, say, height. You can, of course, switch the app’s measurement from standard to metric and in increments of inches, feet, yards, and even miles. (I have no idea how anyone would measure a mile with this thing).

I was careful to move slowly because the faster I rolled, the more the pen roller would slide off a straight line, especially if I didn’t have a hard edge to rest against.

If I rolled past the end of my object, something I did a lot, I could carefully roll backwards, using the laser to line up with the correct edge, while the app simultaneously rolled back the measurement number.

There’s even an Apple Watch app that let me keep track of the measurement number on my wrist.

Instrumments 01 can also measure 3D objects like boxes, and capture curves. When you switch the app to 3D mode, it will recommend you attach the training wheels to the pen. This triangular-shaped attachment slides onto the pen and adds two small rubber wheels backed by two gnarled metal wheels that line up with the roller ring. To measure with the training wheels on, you have to roll them along the surface while they spin the 01’s roll ring. The rougher metal wheels help keep you from slipping around on your measurement surface.

These training wheels help you measure uneven surfaces.

Image: lance ulanoff/mashable

I had a little trouble properly positioning the training wheels. Even when I did figure it out, rolling the pen over 3D objects felt awkward. Plus, the 3D representations that appeared on-screen were useless. Often, it was a jagged line that looked nothing like the box I was trying to measure. One thing I did like is that, in the app, I could turn on a virtual representation of the 01 and watch it move in tandem with the real device (apparently, there’s an accelerometer in it, too).

The laser helps you line up with the edge of whatever you’re measuring.

Image: lance ulanoff/mashable

You can also, according to Instrumments, use 01 to grid out measurements by having the laser blink when, for example, you’ve rolled a foot away from your start point. This could come in handy for hanging photos or finding studs (which are usually 16-inches part) in your walls. Sadly, I couldn’t figure out how that works, and information about the feature is not included in the very basic printed manual (which comes with a free Moleskin-style notebook).

The Instrumments 01 is only a little thicker and heavier than your standard pen.

Image: lance ulanoff/mashable

As for accuracy of the measurements, I would say that depends on the steadiness of your hand and if you can properly align the laser. When I did so, the measurements were perfect. When I got a little sloppy, the measurements became estimates, at best.

Overall, I like the Instrumments 01. Would I pay $149 (or $99) for the convenience of a pen-sized, laser-guided tape measure in my pocket? Probably not, but I could see a carpenter or home decorator using it.

Instrumments 01

The Good

Pen-sized • Simple, smart app • Ingenious measurement ring

The Bad

It forces you to sign up with their service. • 3D measurement is disappointing.

The Bottom Line

Intrumments 01 is a great, pocket-sized measurement system for DIYers, carpenters and home decorators.